The objective of the proposed program is to perform a study on the influence of reinforcement materials on the properties of dental composite restoratives. This will be accomplished by making a systematic study of the influence of shape, size and type. Specifically, the use of shaped particle fillers, such as flakes and ribbons with favorable width-to-thickness ratio, as compared to other regular or irregular particles. The use of selective placement of glass cloth and/or porcelain-coated metal cloth and the use of hybrid reinforcement will be investigated to attain formulas for optimal dental requirements. Much information has been developed in other technological areas showing the superiority of two-dimensional and oriented reinforcements in composite materials over other configurations with regard to strength, modulus, water sorption, wear resistance and dimensional stability. It should be possible to apply this knowledge to obtain a vastly improved dental composite restorative system. This study will involve treating the reinforcing filler, determining methods for optimum orientation of the reinforcement in the composite system, fabricating appropriate test specimens, and conducting a complete evaluation of the composite system. Clinical evaluation will be conducted using the optimum formulation.